The overall goals of the projects described here are to develop a rhesus monkey model for the cognitive effects of NeuroAIDS or MDMA-induces neurotoxicity. NueoAIDS is significant complication od Aids, affecting up to 30% symptomatic patients, while about 5-15% of those with AIDS develop frank dementia. The cognitive and psychomotor disturbances of NeuroAIDS greatly reduce the quality of life of affected individuals and their relations. "Ecstasy," or MDMA is an abused drug with demonstrated neurotoxic potential, but the behavioral effects MDMA-induced neurotoxicity remain to be shown. The behavioral battery developed by Dr. Gold is being used to study both of the topis in rhesus monkey models. The battery presently consists of six tasks which probe aspects of cognitive function mediated by different brain regions. A new task, visuo-spatial paired-associates learning task, will complement the regional sensitivity of the current tests by being sensitive to dysfunction in additional brain areas. The goals of task proposal are 1) to develop this human neuropsychological task for use in rhesus monkeys, 2) to develop additional testing measures for the battery to enhance its sensitivity without additional animal training, and 3) to use these enhancement to characterize cognitive of NeuroAIDS or MDMA-induced neurotoxicity.